Process of precipitaing metals on an incandescent body



May 29, 1928. 1,671,213

A. E. VAN ARKEL ET AL PROCESS OF PRECIPITATING METALS 0N ANINCANDESCENT BODY Filed March 12, 1926 Patented May 29, 1928.

UNITED ANTON EDUABD VAN ARKEL AND JAN HENDRIX DE BOER, F EINDHOVEN, NETHER- LANDS, ASSIGNORS TO N. V. PHILIPS GLOEILAMPENFABRIEKEN, OF EINDHOVEN,-

NETHERLANDS.

PROCESS OF PRECIPITATING METALS ON AN INCANDESCENT BODY.

Application filed March 12, 1926, Serial No. 94,253, and in the Netherlands March 14, 1925.

This invention relates to a process of precipitating chemical compounds on an 1ncandescent body and refers more particularly to a process of precipitating metals of 5 the first. undergroup of the fourth column of the periodic system on such a body.

According to the invention, the process of precipitating the said metals on an incandescent body consists in heating this body in an W atmosphere containing one or more iodides of the metals to be precipitated.

It has already been proposed to precipitate zirconium and titanium on a metal wire by heating the latter in an atmosphere of zirconium chloride or titanium chloride respectively and hydrogen. It has been found,

however, that it is-impossible to precipitate in this manner metallic zirconium or titanium on the metal wire. In these attempts to isolate metallic zirconium or titanium impurities of the hydrogen will presumably have given rise to the isolation of certain zirconium or titanium compounds, for example, nitrides.

Particularly favourable results are obtained with the processaccording to the invention if an incandescent body is heated in an atmosphere containing hafnium iodide so that hafnium is precipitated on said body as the temperature to which the incandescent body can be heated and which depends on the melting point of the metal to be precipitated, can be higher in the case of precipitating hafnium than when precipitating the other metals of the first undergroup o 'the 'fourth column of the periodic system,

since the melting point of hafnium-is higher than that of the other metals of the said undergroup.

The invention will be more clearly understood by referring to an example. The figure represents perspectively by way of example an apparatus suitable for carrying out the process.

The apparatus consists of a vessel 1 in which a wire 2 -made, for example, of tungsten, serves as incandescent body. This tungsten wire is electrically connected, for example, by small screws to leading-in wires 3 and 4 which are hermetically sealed to the narrowed upper end of the vessel. Thus the tungsten wire can be heated to the suitable temperature by an electric current. The vessel is provided with a side-tube 5 which can be connected to a pump and which per-- mits to remove from the vessel 1 the air present therein or other gases having a detrimental influence during the reaction. If zirconium iodide is now introduced into the vessel 1 and if the latter is heated to such a temperature, that the zirconium iodide has a sufiiciently high vapour pressure, which temperature lies between about 400 and 600 (3., the zirconium iodide vapour will be decomposed by heating the tungsten wire to incandescence and metallic zirconium will deposit on the wire. Good results are obtained by heating the tungsten wire to a starting from hafnium iodide, the vapour which is conducted along the wire 2 which f now is heated to beyond 1600 C.

If the filament is heated to a very high. temperature it may occur that the metal precipitated alloys with the tungsten wire, this may occur, for example, when precipitating thorium. The maximal temperature to which the filament can be heated, is there: fore not always determined by the melting temperature of the metal precipitated, but, if the case may be, by the melting temperature of the alloy formed.

In connection with the high temperatures to which the iodides have to be heated in order to evaporate to a sufiicient extent,--it is advisable in some cases that the apparatus for carrying out the process, should not be made of glass but of suitable metals, for example, of chrome iron.

The present application is a continuation in part of application Ser. No. 52,350, filed August 25, 1925.

What we claim is 1. A process of precipitating the metals of the first undergroup of the fourth column of the periodic system on an incandescent body, characterized in that this body is heated in an-atmosphere containing at least one iodide of the metals to be precipitated.

2. A process according to claim 1, characterized in that hafnium is precipitated on the body by heating the latter in an atmosphere of hafnium iodide. i

In testimony whereof we aflix our signatures, at the city of Eindhoven, this 17th day of February, 1926.

ANTON EDUARD VAN ARKEL. JAN HENDRIK DE BOER. 

